<!DOCTYPE html>
<html lang="en">

<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Test</title>
  <style>
    * {
      margin: 0;
      padding: 0;
    }

    h1 {
      width: 100%;
      text-align: center;
      margin-top: 50px;
    }
  </style>
</head>

<body>
  <h1>你好，世界！</h1>
</body>

</html>